Water-soluble polymers are well known for the retention or recovery of certain metal ions from solutions under certain conditions, e.g., certain pH conditions (see, e.g., Pure and Applied Chemistry, Vol. 52, pp. 1883-1905 (1980), Talanta, vol. 36, No. 8, pp. 861-863 (1989), and U.S. Pat. No. 4,741,831). Additionally, higher molecular weight varieties of the water-soluble polymers such as polyethyleneimine have been used as coatings on, e.g., silica, for separation and recovery of metal ions.
Extraction or leaching of selected metals from a solid matrix, such as soil, with various extractants or leachants to recover the selected metals is well known, e.g., the use of cyanide in the mining industry. Such a process can involve placing soil onto an impermeable barrier layer and passing a leachant one or more times through the soil to remove one or more of the metals from the soil. The leachant typically binds with the metal, forming, e.g., a complex. The complex is ultimately separated from the soil, but the metal is not easily concentrated and the leachant is not easily recovered.
It is an object of the present invention to provide a process of separating target metals from a solid matrix such as a soil, an ore, mining tailings, a sludge, an ash, a paint, a catalyst matrix, a solid surface and the like.
It is a further object of the present invention to provide a process of selectively separating target metals from a solid matrix such as a soil, an ore, mining tailings, a sludge, an ash, a paint, a catalyst matrix, a solid surface and the like.
It is a still further object of the invention to provide a process of separating a contaminant metal from a solid matrix such as a soil, an ore, mining tailings, a sludge, an ash, a paint, a catalyst matrix, a solid surface and the like without the generation of significant additional waste.
Still a further object of the present invention is a process of separating a contaminant metal from a solid matrix such as a soil, an ore, mining tailings, a sludge, an ash, a paint, a catalyst matrix, a solid surface and the like whereafter the solid matrix can pass an EPA Toxicity Characteristic Leaching Procedure (TCLP) test for that contaminant metal.
Yet another object of the present invention is a process of separating a metal from a solid matrix such as a soil, a sludge, an ash, a paint, a catalyst matrix and the like using an extractant that can be readily regenerated after use without the generation of significant secondary waste streams.